Spring 2006 Issue

Considerations for Successful
6-Meter EME DXpeditions



As the bottom of the sunspot cycle nears, faithful 6-meter DXers seemingly are stalled in their quest to increase their countries worked totals. The only way around this dilemma is via EME. W7GJ tells how to make those EME QSOs happen on the Magic Band.


By Lance Collister, W7GJ

Until only a few years ago, the prospects of using the moon to complete a 6-meter contact with a rare DXpedition or portable station were extremely remote. However, the increased sensitivity of the recently developed JT65 digital modes by K1JT greatly enhances the viability of such “Ultra Long Path” contacts. It is assumed that JT65A mode will be a key element to success in any 6-meter EME DXpedition, and also that interested 6-meter EME operators are already familiar with this mode. The standard mode for communications on 6-meter EME has become JT65A, which is the most sensitive of the JT65 modes. Detailed instructions of how to effectively use the WSJT software for JT65A EME contacts are available elsewhere and will not be covered here. New JT65 users are urged to review the following sites:

<http://www.bigskyspaces.com/w7gj/JT65checklist.htm>

<http://pulsar.princeton.edu/~joe/K1JT/Documentation.htm>

Our current time near the bottom of the solar cycle is the optimum time for 6-meter EME, and the amount of activity on it has been increasing dramatically. Remember that an EME station with a larger antenna essentially “makes up for” a smaller antenna on the DXpedition end of the circuit. Therefore, the increasing number of larger home stations (both with and without elevation) greatly increases the chances for success by a smaller DXpedition station, provided certain considerations are addressed well in advance. In fact, the portable 6-meter EME station now can probably fill up as much time as is desired on EME contacts, within the constraints of available moon time.

This is by no means to suggest that 6-meter EME is commonplace or trivial. In fact, nothing could be further from the truth! Six meters remains one of the most difficult bands on which to operate moonbounce, and the situation is exacerbated by the fact that 50 MHz signals are high enough in frequency to be affected by tropospheric ducting and low enough to be adversely affected by just about any kind of perturbation in the ionosphere. Of course, too, even when conditions are most favorable for EME, you always run the risk that Faraday rotation will change the polarity so that one (or both) stations will not be able to copy the other! This polarization shift is what makes it very rare for two stations to be copying each other at the same time, and is the reason why EME schedules are often so long—to permit each station to have a chance to exchange required contact information with the other.

 

 

M2 6M7 antenna at OX3LX, March 2005. (Photo courtesy of OZ1DJJ)

Click here to return to Spring 2006 highlights

Click here to subscribe to VHF

_________________

© Copyright 2006, CQ Communications, Inc. All rights reserved. This material may not be reproduced or republished, including posting to a website, in part or in whole, by any means, without the express written permission of the publisher, CQ Communications, Inc. Hyperlinks to this page are permitted.